If you have experience in something, it can be difficult to explain it succinctly to other people.
This may seem counterintuitive. Doesn’t experience give you the advantage of understanding how something works? When you’ve been doing things for a long time, your brain makes part of the process transparent to you. You unconsciously make leaps.
Other times, it’s not that you are taking things for granted that may look like magic to other people. We think that we’ve got a solid understanding of something, when there may be important gaps in our knowledge.
Nobel winning physicist Richard Feynman used a method for learning that relied on teaching. He found that explaining things to others is a great way to learn. His method is now known as the Feynman Technique: Choose a concept. Teach it to a child. Identify the gaps and go back to the source material. Review and simplify.
Give it a try. You’ll find that children are curious and acute. Finding solid explanations for things you thought you knew will help you consolidate that knowledge.